//
// Created by wze-zero on 2024/9/12 012.
//
#include <iostream>
#include <iomanip>

using namespace std;

int main() {
    int num;
    double sum = 0;
    cin >> num;
    for (int i = 1; i < num + 1; ++i) {
        sum += (double) 1 / i;
    }
    cout << fixed << setprecision(6) << sum << endl;
    return 0;
}